Birds which fly in coordinated cluster-flocks can benefit through the formation of group-level structures and patterns which can deter predators by visual confusion. Though unlike V-formation flight, cluster-flocking increases the energetic cost of flight, particularly in denser flocks. Cluster formations therefore provide a unique opportunity to investigate trade-offs between increased work rate (e.g. higher flap frequency) and other benefits of flocking. As part of a routine 9-km training flight release, a flock of six homing pigeons (Columba livia) with 5 Hz GPS and 200 Hz accelerometer biologgers attached flew an alternative trajectory totalling 177 km and 256 min of flight. We provide the first evidence that during a long-duration flight, pigeons’ pairwise and group-level distances increased (i.e. group structure changed), while flap frequency decreased over time. This implies that as birds tire during long-duration flight, the ultimate functions of cluster-flocking—primarily anti-predator benefits—are overridden by the proximate costs of flying close to conspecifics.
CITATION STYLE
Sankey, D. W. E., & Portugal, S. J. (2019). When flocking is costly: reduced cluster-flock density over long-duration flight in pigeons. Science of Nature, 106(7–8). https://doi.org/10.1007/s00114-019-1641-x
Mendeley helps you to discover research relevant for your work.